Perform this simple test using an ordinary 5 gallon plastic bucket to determine if your pool is leaking and losing more water than it should due to its normal evaporation.  Bring pool water to normal level  Fill bucket with pool water to about 1 inch from the top  Place bucket on 1st or 2nd step of the pool  Mark water level on inside of bucket  Shut off pump and mark pool water level on outside of bucket  Resume normal pump operation  After 24 hours, compare the two water levels. If the pool water (outside mark) goes down more than the inside water level, there is probably a leak.  (Test is invalid after 24 hours)